use strict; use warnings; my $l='k '; $l.=sprintf "%3d ",0; for my $k (0..10){ $l.=sprintf " %10s",$k; } print $l."\n"; $l=~s/./-/g; print $l."\n"; for my $n (0..10){ printf "n %3d ",$n; for my $k (0..10){ printf " %10s",fs($n,$k); } print "\n"; } sub fs { my $n=shift; my $k=shift; if ( $n ==0 && $k == 0 ) {return 1}; if ( $k > $n ) {return 0}; # important if ( $n > 0 && $k == 0 ) {return 0} if ( $k == 1 ) {return 1} if ($n == $k ) {return 1} my $p1=fs($n-1,$k-1); my $p2=fs($n-1,$k ); return $p1 + ($k*$p2); }